Wireless transmitter

ABSTRACT

A wireless transmitter includes: a plurality of transmission antennas; a phase rotating unit which adds phase rotation to signals which are respectively input to the plurality of transmission antennas; and a reception unit which receives information on phase control of arbitrary antennas among the plurality of transmission antennas from another party of communication, wherein the phrase rotating unit adds first phase rotation for controlling the maximum delay time between the plurality of transmission antennas depending on whether transmission is performed using frequency diversity or transmission is performed using multi-user diversity and second phase rotation for controlling the phases of the arbitrary antennas among the plurality of transmission antennas based on the information.

This application is a Divisional of co-pending application Ser. No.12/089,361, filed on Apr. 4, 2008, which is a National Phase ofPCT/JP2006/321608 filed on Oct. 30, 2006 which claims priority under 35U.S.C. 119(a) to Patent Application No. JP2005-316549 filed in Japan onOct. 31, 2005, the entire contents of which are hereby incorporated byreference.

TECHNICAL FIELD

The present invention relates to a wireless transmitter.

BACKGROUND ART

In recent years, primarily in multicarrier transmission systems, amethod has been proposed in which scheduling of users is performed bydividing into multiple blocks in frequency and time domains. Here, theregions which are defined in frequency and time domains and are securedwhen users perform communications are called allocated slots, and theblocks that form the basis when determining the allocated slots arecalled chunks.

Amongst these, a method has been proposed that, when transmittingbroadcast/multicast channels or control channels, blocks which are widein the frequency direction are allocated to obtain a frequency diversityeffect, which ensures few errors even with low receiving power, and whentransmitting unicast signals that involve one-on-one communicationbetween a wireless transmitter and a wireless receiver, blocks which arenarrow in the frequency direction are allocated to obtain a multi-userdiversity effect (for example, refer to non-patent document 1 andnon-patent document 2).

FIG. 31 and FIG. 32 show the relationship between time (vertical axis)and frequency (horizontal axis) in signals transmitted from a wirelesstransmitter to a wireless receiver. In FIG. 31, the vertical axisrepresents time, and the horizontal axis represents frequency. In thetime domain, five transmission times t1 to t5 are established. Eachtransmission time t1 to t5 has the same time width. In the frequencydomain, four transmission frequencies f1 to f4 are established. Eachtransmission frequency f1 to f4 has the same frequency width Fc. In thismanner, the transmission times t1 to t5 and the transmission frequenciesf1 to f4 establish 20 chunks K1 to K20 as shown in FIG. 31.

In addition, as shown in FIG. 32, four chunks K1 to K4 are combined inthe frequency direction, and divided into three in the time domaindirection to establish allocated slots S1 to S3 each having a time widthof t1/3 and a frequency width of 4f1. Allocated slot S1 is allocated toa first user, allocated slot S2 is allocated to a second user, andallocated slot S3 is allocated to a third user. Accordingly, the firstto third users are able to obtain a frequency diversity effect.

Next, chunk K5 is allocated to a fourth user as allocated slot S4.Chunks K6 and K7 are combined and allocated to a fifth user as allocatedslot S5. Chunk K8 is allocated to a sixth user as allocated slot S6.Accordingly, the fourth to sixth users are able to obtain a multi-userdiversity effect.

Next, chunks K9 and K11 are allocated to a seventh user as allocatedslot S7. Chunks K10 and K12 are combined, and divided into three in thetime domain direction, to establish communication slots S8 to S10 eachhaving a time width of t3/3 and a frequency width of 2f2. Allocated slotS8 is allocated to an eighth user, allocated slot S9 is allocated to aninth user, and allocated slot S10 is allocated to a tenth user.Accordingly, the seventh to tenth users are able to obtain a frequencydiversity effect.

Next, chunk K13 is allocated to an eleventh user as allocated slot S11.Chunk K14 is allocated to a twelfth user as allocated slot S12. ChunksK15 and K16 are combined and allocated to a thirteenth user as allocatedslot S13. Accordingly, the eleventh to thirteenth users are able toobtain a multi-user diversity effect.

Next, chunks K17 and K19 are allocated to a fourteenth user as allocatedslot S14. Chunks K18 and K20 are combined, and divided into three in thetime domain direction, to establish allocated slots S15 to S17 eachhaving a time width of t5/3 and a frequency width of 2f2. Allocated slotS15 is allocated to a fifteenth user, allocated slot S16 is allocated toa sixteenth user, and allocated slot S17 is allocated to a seventeenthuser. Accordingly, the fourteenth to seventeenth users are able toobtain a frequency diversity effect.

[Non-patent document 1] “Downlink Multiple Access Scheme for EvolvedUTRA”, [online], Apr. 4, 2005, R1-050249, 3GPP, [search conducted onAug. 17, 2005], Internet<URL:ftp://ftp.3gpp.org/TSG_RAN/WG1_RL1/TSGR1_(—)40bis/Docs/R1-050249.zip>

[Non-patent document 2] “Physical Channel and Multiplexing in EvolvedUTRA Downlink”, [online], Jun. 20, 2005, R1-050590, 3GPP, [searchconducted on Aug. 17, 2005], Internet<URL:ftp://ftp.3gpp.org/TSG_RAN/WG1_RL1/R1_Ad_Hocs/LTE_AH_JUNE-050590.zip>

DISCLOSURE OF INVENTION Problems to be Solved by the Invention

The problem to be solved is that in conventional proposed communicationsystems, it is not possible to obtain an adequate multi-user diversityeffect depending on the allocated slot and the location of the wirelessreceiver.

Means for Solving the Problem

The wireless transmitter of the present invention includes: a pluralityof transmission antennas; a phase rotating unit which adds phaserotation to signals which are respectively input to the plurality oftransmission antennas; and a reception unit which receives informationon phase control of arbitrary antennas among the plurality oftransmission antennas from another party of communication, wherein thephase rotating unit adds first phase rotation for controlling themaximum delay time between the plurality of transmission antennasdepending on whether transmission is performed using frequency diversityor transmission is performed using multi-user diversity and second phaserotation for controlling the phases of the arbitrary antennas among theplurality of transmission antennas based on the information.

Furthermore, the wireless transmitter of the present invention is usedin a transmission system in which scheduling of users is performed on aper-chunk basis where a region defined in a frequency domain and in atime domain is divided into chunks in the frequency domain and in thetime domain, and in the case in which the frequency bandwidth of thechunk is Fc, the phase rotating unit adds the first phase rotation sothat the maximum delay time between the plurality of transmissionantennas is set to either a predetermined first value which is smallerthan 1/Fc or a predetermined second value which is larger than 1/Fc.

Moreover, in the wireless transmitter of the present invention, thefirst value is zero.

Moreover, in the wireless transmitter of the present invention, a phaserotation amount added by the second phase rotation is a predeterminedvalue.

Furthermore, the wireless transmitter of the present invention, aplurality values are prepared for the predetermined value, and theinformation includes information for designating a value from among theplurality values.

Moreover, in the wireless transmitter of the present invention, theinformation includes information for designating an antenna to which thesecond phase rotation is added.

Furthermore, the wireless transmitter of the present invention, theinformation includes information indicating a phase rotation amount ofthe second phase rotation which is added to the arbitrary antennas.

Moreover, the wireless transmitter of the present invention may alsoinclude a transmission unit which transmits pilot channels correspondingto the plurality of transmission antennas which are orthogonal to eachother from the plurality of transmission antennas, respectively.

Furthermore, the wireless transmitter of the present invention, each ofthe orthogonal pilot channels is generated by the multiplication of anorthogonal code.

Moreover, the wireless transmitter of the present invention, the phaserotating unit adds no phase rotation to a pilot channel.

Furthermore, the wireless transmitter of the present invention, thephase rotating unit does not add the first phase rotation to a pilotchannel.

Effects of the Invention

The terminal apparatus of the present invention estimates channels withthe base station antennas corresponding to respective pilot channels,and based on the result of applying a predetermined amount of phaserotation to the result of the channel estimation, selects a base stationantenna where applying phase rotation improves the communication state,and calculates the phase rotation amount. Consequently, there is theadvantage that a favorable multi-user diversity effect can be obtained.

Furthermore, the base station apparatus of the present invention appliesphase rotation to respective subcarriers, based on an identification ofa base station antenna selected so as to improve the communicationstate, or a phase rotation amount calculated so as to improve thecommunication state, which are included in the received signal.Consequently, there is the advantage that a favorable multi-userdiversity effect can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing the construction of a communicationsystem in accordance with a first embodiment of this invention.

FIG. 2A is a diagram showing a delay profile of the first embodiment.

FIG. 2B is a diagram showing a transfer function of the firstembodiment.

FIG. 3A is a diagram showing a delay profile of the first embodiment.

FIG. 3B is a diagram showing a transfer function of the firstembodiment.

FIG. 3C is a diagram showing a transfer function of the firstembodiment.

FIG. 4A is a diagram showing a delay profile of the first embodiment.

FIG. 4B is a diagram showing the frequency variation corresponding tothe maximum delay time of FIG. 4A in the first embodiment.

FIG. 5A is a diagram showing a delay profile of the first embodiment.

FIG. 5B is a diagram showing the frequency variation corresponding tothe maximum delay time of FIG. 5A in the first embodiment.

FIG. 6A is an explanatory drawing of a situation where the same signalis transmitted from multiple antennas in the first embodiment withoutadding delay.

FIG. 6B is an explanatory drawing of a situation where the same signalis transmitted from multiple antennas in the first embodiment withoutadding delay.

FIG. 6C is an explanatory drawing of a situation where the same signalis transmitted from multiple antennas in the first embodiment withoutadding delay.

FIG. 7A is an explanatory drawing showing a situation where the samesignal is transmitted from multiple antennas in the first embodimentwith different delays added at respective antennas.

FIG. 7B is an explanatory drawing showing a situation where the samesignal is transmitted from multiple antennas in the first embodimentwith different delays added at each antenna.

FIG. 7C is an explanatory drawing showing a situation where the samesignal is transmitted from multiple antennas in the first embodimentwith different delays added at respective antennas.

FIG. 8 is a diagram showing the signal structure within a chunk in thefirst embodiment.

FIG. 9 is a diagram showing how orthogonal codes are allocated to pilotchannels in the first embodiment.

FIG. 10 is a schematic drawing showing how signals reach a wirelessreceiver from wireless transmitters in the first embodiment.

FIG. 11 is a diagram showing the transfer function between respectivetransmission antennas and a reception antenna, and the transfer functionof the combined wave thereof in the first embodiment.

FIG. 12 is a diagram showing the transfer function between respectivetransmission antennas and a reception antenna, and the transfer functionof the combined wave thereof in the first embodiment.

FIG. 13 is a diagram showing the antenna number notification signal thatis notified from the terminal apparatus to the base station apparatus inthe first embodiment.

FIG. 14 is a diagram showing a terminal apparatus of the firstembodiment.

FIG. 15 is a diagram showing a receiver circuit unit included in theterminal apparatus of the first embodiment.

FIG. 16 is a diagram showing the receiver circuit unit included in theterminal apparatus of the first embodiment.

FIG. 17 is a diagram showing a channel estimating unit included in theterminal apparatus of the first embodiment.

FIG. 18 is a diagram showing a base station apparatus of the firstembodiment.

FIG. 19 is a diagram showing a transmission circuit unit included in thebase station apparatus of the first embodiment.

FIG. 20 is a diagram showing a phase control signal used in the basestation apparatus of the first embodiment.

FIG. 21 is a diagram showing a phase control signal used in the basestation apparatus of the first embodiment.

FIG. 22 is a diagram showing the transfer function between respectivetransmission antennas and a reception antenna, and the transfer functionof the combined wave thereof in the first embodiment.

FIG. 23 is a diagram showing the transfer function between respectivetransmission antennas and a reception antenna, and the transfer functionof the combined wave thereof in a second embodiment of this invention.

FIG. 24 is a diagram showing the transfer function between respectivetransmission antennas and a reception antenna, and the transfer functionof the combined wave thereof in the second embodiment.

FIG. 25 is a diagram showing the antenna number/phase rotation amountnotification signal that is notified from the terminal apparatus to thebase station apparatus in the second embodiment.

FIG. 26 is a diagram showing a terminal apparatus of the secondembodiment.

FIG. 27 is a diagram showing a receiver circuit unit included in theterminal apparatus of the second embodiment.

FIG. 28 is a diagram showing a base station apparatus of the secondembodiment.

FIG. 29 is a diagram showing a phase control signal used in the basestation apparatus of the second embodiment.

FIG. 30 is a diagram showing a phase control signal used in the basestation apparatus of the second embodiment.

FIG. 31 is a diagram showing chunks in a signal transmitted from awireless transmitter to a wireless receiver recited in the backgroundart.

FIG. 32 is a diagram showing the allocated slots in a signal transmittedfrom a wireless transmitter to a wireless receiver in the backgroundart.

DESCRIPTION OF THE REFERENCE SYMBOLS

-   1 Wireless transmitter; 2, 3, 4 Transmission antenna; 5, 6 Delay    device; 7 Wireless receiver; 8 Wireless transmitter; 9, 10 Wireless    receiver; 11 Reception antenna; 17 MAC unit; 18 Physical layer unit;    21 Transmission circuit unit; 22, 122 Reception circuit unit; 23    Wireless frequency converting unit; 24 Antenna unit; 33 A/D    converting unit; 34 GI removing unit; 35 S/P converting unit; 36 FFT    unit; 37 Pilot channel extracting unit; 38 Channel compensating    unit; 39 Demodulating unit; 40 Error correction decoding unit; 41-1,    2, 3 Antenna-specific channel estimating unit; 42 Channel estimating    unit; 43 Phase rotating unit; 44 Adding unit; 45 Switch unit; 46    Control unit; 47 Inversion antenna selecting unit; 48-1, 2, 3    Antenna-specific channel estimating unit; 49 Averaging unit; 50 Code    multiplying unit; 51 Despreading unit; 65 PDCP unit; 66 RLC unit; 67    MAC unit; 68 Physical layer unit; 69 Scheduling unit; 70, 170    Transmission circuit controlling unit; 71 Transmission circuit unit;    72 Reception circuit unit; 73 Wireless frequency converting unit;    74, 75, 76 Antenna unit; 81 a, b User-specific signal processing    unit; 82 Error correction encoding unit; 83 Modulating unit; 84    Subcarrier allocating unit; 85 Pilot channel inserting unit; 86    Phase rotating/weight multiplying unit; 87 IFFT unit; 88    Parallel/serial converting unit; 89 GI adding unit; 90 Filter unit;    91 D/A converting unit; 101-1, 2, 3 Antenna-specific signal    processing unit; 102 Pilot signal generating unit; 103 Weight    calculating unit; 147 Phase rotation amount calculating unit

BEST MODE FOR CARRYING OUT THE INVENTION First Embodiment

A first embodiment of the present invention is described below withreference to the drawings. FIG. 1 is a block diagram showing thestructure of a communication system in accordance with the presentembodiment. FIG. 1 shows that signals transmitted by a wirelesstransmitter 1 travel through a plurality of channels and arrive at awireless receiver 7. The wireless transmitter 1 has a plurality oftransmission antennas 2 to 4, and signals are sent from the respectivetransmission antennas 2 to 4 with different delay times, 0, T, and 2Tapplied to the respective transmission antennas. The wireless receiver 7receives the signals transmitted from the wireless transmitter 1. InFIG. 1, a case is described by way of example, in which the wirelesstransmitter 1 includes three transmission antennas 2 to 4. The pluralityof transmission antennas mentioned here are, by way of example, theantennas installed in a wireless transmitter serving as a base stationfacility for cellular phones or the like, and can be any of three kindsof antenna namely; within the same sector, within the same base stationbut in different sectors, or in different base stations. Here as anexample, a case in which the antennas are installed in the same sectoris described, but other configurations may also be adopted. Furthermore,the delay time T is applied by delay devices 5 and 6 in the figure, thatapply a delay time of T at transmission antenna 3, and a delay time of2T at transmission antenna 4, as mentioned above.

FIG. 2A and FIG. 2B are diagrams showing the delay profile and transferfunction of signal that reach the wireless receiver through a pluralityof (three) channels with different delay times. FIG. 2A shows a delayprofile in terms of time (horizontal axis) and power (vertical axis) oftransmission signals that reach a wireless receiver through a pluralityof channels with different delay times. As shown in FIG. 2A, theinstantaneous delay profile has a maximum delayed wave of 2T+dmax, whichis a greater maximum delayed wave than if the same signal weretransmitted from the respective transmission antennas. Here, dmaxindicates the difference between the arrival times of the radio wavesthat traveled from the transmission antennas to the reception antennaover the fastest channel and those that traveled over slower channels.

FIG. 2B shows a transfer function in terms of frequency (horizontalaxis) and power (vertical axis) obtained by frequency-converting thedelay profile in FIG. 2A. In this manner, an increase in the maximumdelay time 2T+dmax in the delay profile means more rapid variation inthe transfer function due to frequency. Accordingly, as shown in FIG.2B, data D1 and D2 are each spread at a spreading factor of four andsubcarriers are allocated. Preferably the spreading factor or the codingrate of an error-correcting code is controlled on the wirelesstransmitter 1 side in accordance with the variation in the transferfunction due to frequency. However, in the above method, because thedelay time 2T is already known at the wireless transmitter 1 side, thespreading factor or code rate of the error-correcting code can bedetermined without regard to the variation of the channel due tofrequency.

One the one hand, in order to obtain a multi-user diversity effect,preferably the maximum delay time 2T+dmax in the instantaneous delayprofile is not particularly large. FIG. 3A, FIG. 3B, and FIG. 3C arediagrams showing the delay profile and transfer function of signals thatreach a wireless receiver through a plurality of channels with differentdelay times. FIG. 3A shows a delay profile in terms of time (horizontalaxis) and power (vertical axis) which represents the arrival oftransmission signals at a wireless receiver through a plurality of(three) channels with different delay times. FIG. 3B shows the transferfunction at the wireless receiver used by user u1. Moreover FIG. 3Cshows the transfer function at the wireless receiver used by user u2.Because the wireless receivers of user u1 and user u2 are at differentlocations, the instantaneous transfer functions are different. In otherwords, deeming the regions on the left side of FIG. 3B and FIG. 3Cfrequency channel b1, and the regions on the right side frequencychannel b2, user u1 obtains better quality in frequency channel b2, anduser u2 obtains better quality in frequency channel b1. Accordingly, thedata D1 to D4 are transmitted to user u1 over frequency channel b2. Thedata D1 to D4 are transmitted to user u2 over frequency channel b1.

In this manner, by utilizing the quality difference between frequencychannels at a particular instant, a multi-user diversity effect thatimproves transmission efficiency can be obtained by having differentusers communicate over respective frequency channels. However, if themaximum delay time 2T+dmax is too large, the speed of variation in thetransfer function due to frequency increases, which reduces the qualitydifference between the frequency channel 1 and the frequency channel 2.Accordingly, in order to obtain an adequate multi-user diversity effect,it is important that the maximum delay time 2T+dmax is small, as shownin FIG. 3A.

FIG. 4A, FIG. 4B, FIG. 5A, and FIG. 5B are diagrams showing therelationship between the maximum delay time (n−1)T and frequencyvariation. As shown in FIG. 4A, when the difference between the arrivaltimes of the two incoming waves w31 and w32 is (n−1)T, the transferfunction of this channel is as shown in FIG. 4B. In other words, theinterval between falls in the amplitude of the power (vertical axis) canbe expressed as F=1/(n−1)T. Furthermore, as shown in FIG. 5A, when aplurality of delayed waves w41 to w42 exist, if the difference betweenthe arrival times of the first incoming wave to arrive w41 and the lastdelayed wave to arrive w43 is (n−1)T, then as expected the frequencyinterval between falls in the amplitude of the power (vertical axis) isF=1/(n−1)T as shown in FIG. 5B.

Incidentally, as previously mentioned, because the appropriate variationin the transfer function due to frequency differs in cases where afrequency diversity effect is desired and in cases where a multi-userdiversity effect is desired, then in the case where a frequencydiversity effect is desired, by setting the maximum delay time (n−1)Tbetween transmission antennas to (n−1)T>1/Fc, where Fc is the frequencybandwidth of a chunk which is a fundamental region defined in thefrequency and time domains and is secured when users performcommunication, an environment can be produced in which a frequencydiversity effect can be readily obtained. In contrast, when a multi-userdiversity effect is desired, by setting the maximum delay time (n−1)Tbetween transmission antennas to (n−1)T<1/Fc, where Fc is the frequencybandwidth of a chunk, an environment can be produced in which amulti-user diversity effect can be readily obtained. Furthermore, in thedescription that follows, (n−1)T<1/Fc is taken to also include (n−1)T=0.Also in the description that follows, the delay time added to respectiveantennas is expressed as n−1 times T, and T is assumed to be constant,but different values of T may be used for the respective antennas.Moreover, when a multi-user diversity effect is desired, another way toreduce the maximum delay time, instead of using a setting of(n−1)T<1/Fc, is to reduce the number of transmission antennas used totransmit the signals.

As described above, by transmitting the transmission signals usingfrequency diversity or using multi-user diversity (by setting either(n−1)T>1/Fc or (n−1)T<1/Fc), a frequency diversity effect or amulti-user diversity effect can be obtained without being affected bythe state of the channel.

Transmission using frequency diversity and transmission using multi-userdiversity can be switched in accordance with such factors as the type ofsignal being transmitted (pilot signal, control signal,broadcast/multicast signal or the like) or the speed at which thewireless receiver is moving (frequency diversity when the receiver istraveling quickly and multi-user diversity when the receiver istraveling slowly).

FIG. 6A through FIG. 6C are explanatory drawings showing thetransmission of the same signal from multiple antennas of a wirelesstransmitter 8 without the application of delay time. Considering asituation as shown in FIG. 6A where the wireless transmitter 8 includesa plurality of (three) horizontally omnidirectional transmissionantennas arranged in parallel, because the elliptical lobes e11 and e12shown in FIG. 6A are produced, receivers in certain directions such aswireless receiver 9 are able to receive the reception signal across theentire frequency band with a high reception level (refer to FIG. 6B),but receivers in other directions such as wireless receiver 10 receivethe reception signal at a low reception level across the entire band(refer to FIG. 6C).

FIG. 7A through FIG. 7C are explanatory drawings showing thetransmission of the same signal from multiple antennas of the wirelesstransmitter 8, with different delay times applied. Considering asituation as shown in FIG. 7A where the wireless transmitter 8 includesa plurality of (three) horizontally omnidirectional transmissionantennas arranged in parallel, and assuming a narrow band, because theelliptical lobes e21 to e26 shown in FIG. 7A are produced, certainfrequency bands in the received signal have high reception levels andother frequency bands have low reception levels, but the average levelof the received signal is fairly constant regardless of direction.Consequently, in terms of the reception level of the signals at thewireless receiver 9 (refer to FIG. 7B) and at the wireless receiver 10(refer to FIG. 7C), substantially the same quality is obtained at bothreceivers. Accordingly, the method of transmitting signals by applyingdifferent delay times at respective antennas of the wireless transmitter8 can overcome the deficiencies associated with transmitting the samesignal from each of multiple antennas as explained with reference toFIG. 6A to FIG. 6C.

FIG. 8 shows the signal structure within a chunk in the presentembodiment. FIG. 8 shows the signal structure within the chunk K1 inFIG. 31 in detail. In this example, chunk K1 includes 19 subcarriersarranged in the frequency direction (horizontal axis direction) and fourOFDM (Orthogonal Frequency Division Multiplexing) symbols arranged inthe time direction (vertical axis). Furthermore, the shaded portions p1to p10 in the figure constitute the Common Pilot Channel (CPICH), usedto estimate the channel during demodulation and to measure aspects suchas the quality of the received signal. The foregoing structure is thesame for chunks K1 to K20. Furthermore in the description below, thecommon pilot channel and dedicated pilot channel are referred tocollectively as the pilot channels (the pilot channels in the claims).Delay time is added to the data signal portion only, not to the pilotchannels. Moreover, the dedicated pilot channel is added for the purposeof complementing the common pilot channel, and is used for such purposesas estimating channels during demodulation.

Moreover the non-shaded portions in FIG. 8 are subcarriers which areallocated to the data signals used to carry data channels and controlchannels.

Next, FIG. 9 shows an example where orthogonal codes A, B, and C areallocated to the common pilot channel shown in FIG. 8. The common pilotchannel is a pilot channel that is received at all terminals. In FIG. 9,the horizontal axis represents frequency, and the curved shapes at thetop of the figure indicate subcarriers.

The shaded subcarriers at the top of the figure correspond to the commonpilot channel described in FIG. 8, and orthogonal codes A, B, and C areallocated to this common pilot channel. In FIG. 9, because the commonpilot channel is allocated to every second subcarrier, the orthogonalcodes are also allocated to every second subcarrier. In the presentembodiment, the orthogonal codes (here orthogonal codes A, B, and C) areallocated, respectively, to the common pilot channel transmitted fromeach of the transmission antennas 2, 3, and 4 shown in FIG. 1(hereinafter it is assumed that these antennas are allocated antennanumber 1, 2, and 3 respectively). Consequently, for example if thecommon pilot channel transmitted from the transmission antenna 2 ismultiplied by the orthogonal code A, then by multiplying the commonpilot channels P1 to P4 by a complex conjugate of the orthogonal code Aand adding the results, a transfer function that depicts the channelresponse in the frequency domain between the transmission antenna 2 andthe reception antenna 11 can be determined even when the common pilotchannels are transmitted concurrently from the other transmissionantennas 3 and 4.

Furthermore, by repeating this process from common pilot channel P4 h+1to common pilot channel P4 h+4 (where h is a natural number), thetransfer function between the transmission antenna 2 (the transmissionantenna 3, or the transmission antenna 4) and the reception antenna 11can be determined in the same manner.

Next, FIG. 10 shows a simplified version of FIG. 1. The two are the samein that signals are transmitted from a transmitter 1 through threetransmission antennas 2, 3, and 4 and received at a receiver 7, butdiffer in that the transfer function of the channel between thetransmission antenna 2 and the reception antenna 11 is labeled H1, thetransfer function between the transmission antenna 3 and the receptionantenna 11 is labeled H2, and the transfer function between thetransmission antenna 4 and the reception antenna 7 is labeled H3.Furthermore, as in FIG. 1, delay devices 5 and 6 add a delay of time T.

Although in practice the transmission signals transmitted from thetransmitter 1 are presumed to reach the receiver 7 through a multi-pathenvironment as shown in FIG. 1, here for the sake of simplicity a singlepath environment is depicted.

In the environment shown in FIG. 10, the transfer function of thecombined waves of the transmission antennas 2 to 4 for the receivedsignals that reach the receiver 7 from the transmitter 1 can beexpressed as in FIG. 11, by taking into consideration the delay added bythe delay devices 5 and 6 as well as the transfer functions H1 to H3. InFIG. 11, the horizontal axis is the real axis, and the vertical axis isthe imaginary axis.

Here, assuming a delay of T is added to the transmission antenna 3 and adelay of 2T is added to the transmission antenna 4, the phase rotationamount θ in FIG. 11 corresponds to the delay amount T, and can beexpressed as θ=2 πm′T/Ts. Here m′ is the subcarrier number of the middlesubcarrier of the chunk used for communication between the transmitter 1and the receiver 7 (for example chunk K1). Furthermore, Ts indicates theuseful symbol duration of the OFDM symbol. Accordingly, because thevalue of θ can be calculated once the chunk used for communication andthe delay time T for each transmission antenna are determined, byutilizing the properties of the orthogonal codes to calculate thetransfer functions H1 to H3 between the transmission antennas 2 to 4 andthe reception antenna 8, H1, H2 e ^(jθ), and H3 e ^(j2θ), which are thetransfer functions after delay is added at each transmission antenna,and H1+H2 e ^(jθ)+H3 e ^(j2θ), which is the transfer function aftercombining, can be calculated.

On the one hand, once the transfer functions H1, H2 e ^(jθ), and H3 e^(j2θ) after delay is added at each transmission antenna can becalculated, then if, using for example H1 as a references, a vector ofthe transfer function after delay is added at each transmission antenna(here H3 e ^(j2θ)) appears in a position opposite H1 over a dashedstraight line which passes through the origin and is perpendicular toH1, then it can be understood that the transmission antenna 4 is workingso as to weaken the received signals. Accordingly, by transmitting asignal from the base station with the phase inverted at the transmissionantenna 4, the signal from the transmission antenna 4 can be utilized soas to enhance the received signals as shown in FIG. 12, giving thetransfer function H1+H2 e ^(jθ)+H3 e ^(j(2θ+π)) after combining a largeramplitude (improved reception quality) than in FIG. 11. Incidentally,applying the foregoing case to FIG. 3B, a situation where signalsreceived from the respective transmission antennas weaken each other asin FIG. 11, leading to poor reception quality, corresponds to frequencychannel b1 in FIG. 3B, and a situation where signals received from therespective transmission antennas strengthen each other, leading to goodreception quality, corresponds to frequency channel b2 in FIG. 3B.

Thus, because the transfer functions H1, H2 e ^(jθ), and H3 e ^(j2θ)after delay is added at each transmission antenna can be measured onlyat the terminal apparatus, and phase control such as “inverting thephase of the transmission antenna 4” can be performed only at the basestation, information about whether or not phase inversion is requiredfor each antenna number is provided from the terminal apparatus to thebase station in the form of a binary signal as shown in FIG. 13.

The apparatus configuration of a terminal apparatus and base stationapparatus that operate as above is described below. First, the apparatusconfiguration of the terminal apparatus is shown in FIG. 14. Theterminal apparatus includes: a MAC (Media Access Control) unit 17 thatperforms ARQ (Automatic Repeat reQuest) processing, schedulingprocessing, and data assembly and disassembly, as well as controlling aphysical layer unit 18, including transferring data received from ahigher layer (not shown) to the physical layer unit 18 and transferringdata transferred from the physical layer unit 18 to the higher layer(not shown); the physical layer unit 18 that, under the control of theMAC unit 17, converts the transmission data transferred from the MACunit 17 into a wireless transmission signal, and passes receivedwireless signals to the MAC unit 17. Furthermore, the MAC unit 17notifies a reception circuit unit 22 of the phase rotation amount θshown in FIG. 11 and FIG. 12, and the reception circuit 22 notifies theMAC unit 17 of obtained information about whether or not phase inversionis required for each antenna number (FIG. 13) as an antenna numbernotification signal.

Furthermore, the physical layer unit 18 includes: a transmission circuitunit 21 that modulates the transmission data notified from the MAC unit17 and transfers to a wireless frequency converting unit 23; thereception circuit unit 22 that demodulates the output from the wirelessfrequency converting unit 23 and passes to the MAC unit 17; the wirelessfrequency converting unit 23 that converts transmission signals passedfrom the transmission circuit unit 21 into a wireless frequency, andconverts reception signals received by an antenna unit 24 into afrequency band able to be processed by the reception circuit unit 22;and the antenna unit 24 that transmits transmission signals passed fromthe frequency converting unit 23, and receives signals. The fundamentalroles of these constituent elements, with the exception of the receptioncircuit unit 22, are described in the following reference documents (1)and (2).

-   (1) 3GPP contribution, R2-051738, “Evolution of Radio Interface    Architecture”, URL:    ftp://ftp.3gpp.org/TS_GRAN/WG2_RL2/TSG2_AHs/2005_(—)06_LTE/Docs/R2-051738.zip-   (2) 3GPP contribution, R1-050248, “Uplink Multiple Access Scheme for    Evolved UTRA”, URL:    ftp://ftp.3gpp.org/TSG_RAN/WG1_RL1/TSGR1_(—)40bis/Docs/R1-050248.zip

Next, the reception circuit unit 22 is described with reference to FIG.15. The reception circuit 22 includes: an A/D converting unit 33 thatperforms analog/digital conversion of the output of the wirelessfrequency converting unit 23 (FIG. 14); a GI removing unit 34 thatremoves a guard interval (GI) from the output of the A/D converting unit33; an S/P converting unit 35 that performs serial/parallel conversionof the output of the GI removing unit 34; an FFT (Fast FourierTransform) unit 36 that performs time/frequency conversion of the outputof the S/P converting unit 35; a pilot channel extracting unit 37 thatseparates pilot channels from a data signal in the output of the FFTunit 36; antenna-specific channel estimating units 41-1 to 41-3 that usethe pilot channels to derive the “transfer functions after delay isadded at each transmission antenna” for the antennas numbered 1 to 3; anadding unit 44 that adds the outputs of the antenna-specific channelestimating units 41-1 to 41-3 for respective subcarriers; a switch unit45 that switches between the output of the adding unit 44 and the outputof a channel estimating unit 42 under the control of a control unit 46;a channel compensating unit 38 that applies channel compensation to adata signal using the output of the switch unit 45 as a channelestimation value; a demodulating unit 39 that performs demodulationprocessing such as QPSK (Quadrature Phase Shift Keying) or 16 QAM(Quadrature Amplitude Modulation) on the output of the channelcompensating unit 38; and an error correction decoding unit 40 thatperforms error-correction decoding on the output of the demodulatingunit 39.

Furthermore, the antenna-specific channel estimating unit 41-1 includes:the channel estimating unit 42 that calculates a channel estimationvalue for each transmission antenna based on the pilot channel signalextracted from the received signal by the pilot channel extracting unit37; and a phase rotating unit 43 that multiplies the output of thechannel estimating unit 42 by an amount of phase rotation θmcorresponding to the delay for each transmission antenna. An inversionantenna selecting unit 47 uses the outputs of the phase rotating unit 43to determine which transmission antennas are to be subjected to phaserotation by a predetermined phase amount as shown in FIG. 11 and FIG. 12(here, the predetermined phase amount is π, which inverts the phase),and notifies the MAC unit 17 of the result as the antenna numbernotification signal. The MAC unit 17 outputs this antenna numbernotification signal to the transmission circuit unit 21 (FIG. 14) astransmission data, and the data is then transmitted via the wirelessfrequency converting unit 23 and the antenna unit 24.

The antenna-specific channel estimating units 41-2 and 41-3 have thesame construction as the antenna-specific channel estimating unit 41-1.Furthermore, a situation in which the switch unit 45 uses the output ofthe channel estimating unit 42 as the channel estimation valuecorresponds to (for example) when a data signal is only transmitted fromthe transmission antenna allocated antenna number 1 (no transmissiondiversity is performed), and a situation in which the switch unit 45uses the output of the adding unit 44 as the channel estimation valuecorresponds to (for example) when CDTD (Cyclic Delay Transmit Diversity)is performed. The value θm above is defined as θm=2 πm(n−1)T/Ts, where mis the subcarrier number, Ts is the useful symbol duration of the OFDMsymbol, and (n−1)T is the delay time applied to the transmission antennaallocated antenna number n.

Furthermore, delay is added only to the data signal portion, not to thepilot channel.

On the one hand, the reception circuit unit 22 shown in FIG. 16 hassubstantially the same construction as that shown in FIG. 15, with theexception that the antenna-specific channel estimating unit 48-1 has anaveraging unit 49. In FIG. 15, the inversion antenna selecting unit 47uses the middle subcarrier of the chunk used for communication by thetransmitter 1 and receiver 7 (for example chunk K1) as shown in FIG. 11and FIG. 12, but in FIG. 16, the averaging unit 49 is provided thataverages the outputs for multiple subcarriers from the phase rotatingunit 43 calculated from the pilot channels in the chunk, and theinversion antenna selecting unit 47 uses the output of the averagingunit 49, and thus antennas can be selected using the average transferfunction within the chunk.

Furthermore, FIG. 17 shows the channel estimating unit 42 of FIG. 15 andFIG. 16 in detail. As shown in the figure, the input to the channelestimating unit 42 enters a code multiplying unit 50. To determine thetransfer function from the transmission antenna 2 allocated, forexample, antenna number 1, the input signal is multiplied by a complexconjugate of code A (refer to FIG. 9) in the code multiplying unit 50,and then added in a despreading unit 51 over the period of theorthogonal code (in the case of code A in FIG. 9, adding for 4 pilotchannels). Accordingly, the channel estimating unit 42 output candetermine the transfer function of the channel from the desired antenna.Information about the orthogonal code and period thereof is notifiedfrom the control unit 46.

Next, FIG. 18 shows the construction of the base station apparatus. Thebase station apparatus includes: a PDCP (Packet Data ConvergenceProtocol) unit 65 that receives IP packets, performs such processing ascompressing headers thereof, transfers to an RLC (Radio Link Control)unit 66, and decompresses the headers so as to convert data receivedfrom the RLC unit 66 into IP packets; the RLC (Radio Link Control) unit66 that transfers data received from the PDCP unit 65 to a MAC (MediaAccess Control) unit 67 and also transfers data transferred from the MACunit 67 to the PDCP unit 65; the MAC (Media Access Control) unit 67 thatperforms ARQ processing, scheduling processing, and data assembly anddisassembly, as well as controlling a physical layer unit 68,transferring data transferred from the RLC unit 66 to the physical layerunit 68 and transferring data transferred from the physical layer unit68 to the RLC unit 66; and the physical layer unit 68 that, under thecontrol of the MAC unit 67, converts transmission data transferred fromthe MAC unit 67 into wireless transmission signals, and transferswireless reception signals to the MAC unit 67.

Furthermore, the MAC unit 67 includes: a scheduling unit 69 thatdetermines the allocated slots to use to communicate with each terminalcommunicating with the base station apparatus; and a transmissioncircuit controlling unit 70 that controls the transmission circuit unit71 using “subcarrier allocation information” based on “chunk allocationinformation” received from the scheduling unit 69, and uses a phasecontrol signal to control the delay time between the antennas dependingon a frequency diversity region or multi-user diversity region, as shownin FIG. 2 and FIG. 3. In addition, in the MAC unit 67, the transmissioncircuit controlling unit 70 uses the antenna number notification signal,which is notified from the reception circuit 72 based on the receivedsignal, to control the transmission circuit 71 through the phase controlsignal.

Furthermore, the physical layer unit 68 includes: the transmissioncircuit unit 71 that performs modulation of data notified from the MACunit 67 under the control of the transmission circuit controlling unit70 and notifies the wireless frequency converting unit 73; the receptioncircuit unit 72 that demodulates the output of the wireless frequencyconverting unit 73 and passes to the MAC unit 67; the frequencyconverting unit 73 that converts transmission signals passed from thetransmission circuit unit 71 into a wireless frequency, and convertsreception signals received by antenna units 74 to 76 into a frequencyband able to be processed by the reception circuit unit 72; and theantenna units 74 to 76 that transmit transmission signals passed fromthe frequency converting unit 73 into wireless space and receive signalsfrom the wireless space. With the exception of the transmission circuitunit 71, which is a feature of the present invention, the details of theroles of these constituent elements are described in reference documents(1) and (2) mentioned above, and detailed description thereof is omittedhere.

Next, FIG. 19 shows the construction of the transmission circuit unit 71in the present embodiment. As shown in FIG. 19, the transmission circuitunit 71 includes: user-specific signal processing units 81 a and 81 bthat process signals destined for respective users; a pilot signalgenerating unit 102 that generates pilot channel signals which are used,for example, for channel estimation in the terminals, orthogonal codeswhich are orthogonal with each other being allocated to the respectiveantennas, and inputs them into a pilot channel inserting unit 85; asubcarrier allocating unit 84 that allocates the outputs of theuser-specific signal processing units 81 a and 81 b to respectivesubcarriers; and antenna-specific signal processing units 101-1, 101-2,and 101-3 that process the signals for the respective antennas.

The user-specific signal processing unit 81 a includes an errorcorrection encoding unit 82 that performs error-correction encoding oftransmission data, and a modulating unit 83 that performs modulationprocessing such as QPSK or 16 QAM on the output of the error correctionencoding unit. The outputs from the user-specific signal processingunits 81 a and 81 b are allocated to suitable subcarriers in thesubcarrier allocating unit 84 which allocates to suitable subcarriersbased on the “subcarrier allocation information” notified from thetransmission circuit controlling unit 70 (refer to FIG. 18), and arethen output to the antenna-specific signal processing units 101-1 to101-3. In the antenna-specific signal processing unit 101-1, the pilotchannel inserting unit 85 allocates the output of the pilot channelgenerating unit 102 to the positions (subcarriers) for the common pilotchannels as shown in FIG. 8, based on the outputs of the subcarrierallocating unit 84 and the output of the pilot channel generating unit102.

Furthermore, the outputs of the pilot channel inserting unit 85 areinput into a phase rotating/weight multiplying unit 86, in which a phaserotation θm or weight wm is multiplied for respective subcarriers, andthe result is output to an IFFT (Inverse Fast Fourier Transport: inversefast Fourier converting unit) unit 87. Then, the output of the IFFT unit87 is subjected to parallel-to-serial conversion in a parallel/serialconverting unit 88, and a guard interval is added to the output of theparallel/serial converting unit 88 by a GI adding unit 89.

In addition, a filter unit 90 extracts only a signal of a desiredbandwidth in the output of the GI adding unit 89, and a D/A convertingunit 91 performs digital/analog conversion of the output of the filterunit 90 and outputs. This output serves as the output of theantenna-specific signal processing unit 101-1.

Furthermore, the antenna-specific signal processing units 101-2 and101-3 have a similar construction. The outputs of the antenna-specificsignal processing units 101-1, 101-2, and 101-3 each pass through thewireless frequency converting unit 73 (refer to FIG. 18) which performsfrequency-conversion into a wireless frequency and then output to theantennas 74, 75, and 76 (refer to FIG. 18) for transmission as awireless signal. When phase rotation is added by the phaserotating/weight multiplying unit 86, the phase rotation is θm, which isnotified from the transmission circuit controlling unit 70 as the phasecontrol signal based on the antenna number notification signal includedin the reception signal received by the base station apparatus. Thedetails thereof will be described below. Furthermore, whenmultiplication by a weight wm takes place in the phase rotating/weightmultiplying unit 86, directivity control can be performed by setting theweight in the manner shown below.

Assuming a linear array of n antennas where the element separation is ahalf wavelength of the carrier frequency, an example of the weight wmcan be expressed as follows:

$\begin{matrix}{w_{m} = {\frac{1}{\sqrt{n}}\left\{ {{\mathbb{e}}^{j\; k\;\pi\;\sin\;{\theta \cdot {({0 - \frac{n - 1}{2}})}}},{\mathbb{e}}^{j\; k\;\pi\;\sin\;{\theta \cdot {({1 - \frac{n - 1}{2}})}}},\ldots\mspace{14mu},{\mathbb{e}}^{j\; k\;\pi\;\sin\;{\theta \cdot {({{({n - 1})} - \frac{n - 1}{2}})}}}} \right\}}} & \left\lbrack {{Equation}\mspace{14mu} 1} \right\rbrack\end{matrix}$

Here, wm is the weight used by the weight multiplying circuit expressedas a vector, where the first element corresponds to the weight used forantenna number 1, the second element corresponds to the weight used forantenna number 2, and the nth element corresponds to the weight used forantenna number n, and so on. In the wm given above, n is the number ofantennas (n=3 in the present embodiment), θ′ is the direction of themain beam, and k is the ratio between the frequency at which the signalis to be transmitted and the frequency at which θ′ was measured.

Here, as the direction θ′ of the main beam, a value measured by areceiver or the terminal of the other party of communication is notifiedto a weight calculating unit 310 and used when deriving the weight wm.The wm given above is only one example, and a method of deriving θ′ andwm is proposed in detail in the following reference document:

“IEICE Technical Report RCS2004-229”, published November 2004 by theInstitute of Electronics, Information, and Communication Engineers

In FIG. 19, a situation involving two users and three antennas wasdescribed, but naturally a similar construction can be employed forother situations.

Subsequently, FIG. 20 relates to the phase control signal. As shown inFIG. 20, in phase control, different phase rotation is applied forrespective antennas (antenna numbers 1, 2, and 3), respectivesubcarriers (subcarrier m), against the pilot channel and the datasignal, and for respective chunks (or allocated slots) used forcommunication (the delay amount T differs as shown in FIG. 2 and FIG.3). In concrete terms, in the present embodiment, no delay amount isadded to the pilot channel at any antenna, and no delay amount is addedto the antenna designated antenna number 1. Regarding the delay time, adelay time of T is added at antenna number 2 to the data signal portiononly, and a delay time of 2T is added at antenna number 3. In addition,regarding the phase inversion based on the antenna number notificationsignal notified from the terminal, in this case antenna number 3 isnotified as shown in FIG. 13, and the phase inversion is performed forthe antenna designated antenna number 3.

In this case, regarding the phase rotation amount θm of the phasecontrol signal, the phase rotation amount θm is always 0 for the pilotchannel regardless of the antennas, and for the data signal portion, itis 0 for antenna number 1, 2 πmT/Ts for antenna number 2, and 2πm2T/Ts+π for antenna number 3. In the phase rotating/weight multiplyingunit 86, phase rotation is implemented based on the phase controlsignal. If the antenna number notification signal notified from theterminal indicates an antenna other than antenna number 3, the phase ofthat antenna is controlled by adding π. Here T is the delay time betweenantenna number 1 and antenna number 2, and can be a different value forrespective chunks (or allocated slots) used for communication. Moreover,m is the subcarrier number, and Ts is the useful symbol duration of theOFDM symbol.

A different case in which the phase control information shown in FIG. 21is used is described in the same manner. The phase control informationin FIG. 21 is substantially the same as that in FIG. 20, with theexception of the phase control information related to the pilot channelof antenna number 3. In this case, the phase inversion operation isperformed in the phase rotating/weight multiplying unit 86 on not onlythe data signal but also the pilot channel of the antenna whose antennanumber is included in the antenna number notification signal notifiedfrom the terminal, and the use of such phase control informationdistinguishes FIG. 21 from FIG. 20. Furthermore, in this case, the phaserotation amount added in the phase rotating unit included in theantenna-specific channel estimating unit 41-3 on the terminal apparatusside in FIG. 15 also differs from FIG. 12, and because the state afterphase rotation of π is added to the pilot channel is observed (H3′),only the phase rotation 2θ corresponding to the delay time added to eachantenna is added at the phase rotating unit 43 and used in thedemodulation as channel estimation information (refer to FIG. 22).

Thus, by using a communication system including the terminal apparatusand the base station apparatus set forth in the present embodiment, evenwhen the maximum delay time between antennas is small particularly asshown in FIG. 3A, a large multi-user diversity effect can be obtained byperforming the phase control described in the present embodiment. In thepresent embodiment, an example was used in which the phase of eachantenna is inverted, that is, the phases are changed by π, but this isnot limited to π, and a variety of values such as π/4 and π/3 can beused to achieve similar techniques, although a detailed descriptionthereof is omitted here.

Second Embodiment

In the present embodiment, a system is described in which the phaserotation amount for each antenna is measured in the terminal and isnotified to the base station. FIG. 23 is substantially the same as FIG.10, except that by adding the phase rotation amount required to alignthe phases at H1, that is, adding phase rotation amount of θ2 to thesignal H2 e ^(jθ) from the antenna designated antenna number 2 (in thiscase transmission antenna 3) and phase rotation amount of θ3 to thesignal H3 e ^(j2θ) from the antenna designated antenna number 3 (in thiscase transmission antenna 4), the received signals from the threetransmission antennas can be added in an in-phase and received at theterminal.

This situation is shown in FIG. 24. That is, the transfer functions ofrespective antennas after delay is added are H1, H2 e ^(jθ), and H3 e^(j2θ). Although the combined transfer function thereof is H1+H2 e^(jθ)+H3 e ^(j2θ), it can be understood that by adding phase rotation ofθ2 to the antenna designated antenna number 2 (transmission antenna 3)and phase rotation of θ3 to the antenna designated antenna number 3(transmission antenna 4) beforehand at the base station, the resultingtransfer functions after phase rotation is performed and delay is addedat respective antennas are H1, H2 e ^(j(θ+θ2)), and H3 e ^(j(2θ+θ3)),and the amplitude of the combined transfer function H1+H2 e^(j(θ+θ2))+H3 e ^(j(2θ+θ3)) thereof is larger than that of FIG. 23.Incidentally, applying the above case to FIG. 3B, a situation as in FIG.11 where signals received from the respective transmission antennasweaken each other, leading to poor reception quality, corresponds tofrequency channel b1 in FIG. 3B, and a situation as in FIG. 12 wheresignals received from the respective transmission antennas strengtheneach other, leading to good reception quality, corresponds to frequencychannel b2 of FIG. 3B.

In this manner, because the transfer functions H1, H2 e ^(jθ), and H3 e^(j2θ) after delay is added at each antenna can be measured only at theterminal apparatus, and phase control per antenna such as θ2 and θ3 canbe performed only at the base station apparatus, the terminal apparatusmust notify the base station apparatus of the phase rotation amounts forrespective antenna numbers as shown in FIG. 25.

Subsequently, the apparatus configuration of the terminal apparatus ofthe present embodiment is shown in FIG. 26. The terminal apparatusrecited in FIG. 26 is substantially the same as that described in thefirst embodiment with reference to FIG. 14, but differs in that thereception circuit unit 122 is different and an antenna number/phaserotation amount notification signal shown in FIG. 25 is notified fromthe reception circuit unit 122 to the MAC unit 17. Moreover, the MACunit 17 uses the antenna number/phase rotation amount notificationsignal as transmission data, the transmission circuit unit 21 performsmodulation processing and performs communication with the base station.Subsequently, the reception circuit unit 122 shown in FIG. 26 is nowdescribed in detail with reference to FIG. 27. FIG. 27 is substantiallythe same as FIG. 15, with the exception that the inversion antennaselecting unit 47 is replaced by a phase rotation amount calculatingunit 147. The phase rotation amount calculating unit 147 calculates thephase rotation amount required to align the phases at respectiveantennas with the transfer function H1 as shown in FIG. 23 and FIG. 24using the output of the phase rotating unit 43, and notifies the MACunit 17 as the antenna number/phase rotation amount notification signal.Alternatively, the output of the averaging unit 49 can be input into thephase rotation amount calculating unit 147 in the same manner as in FIG.16 of the first embodiment.

Next, the structure of the base station apparatus in the presentembodiment is described with reference to FIG. 28. The construction ofFIG. 28 is substantially the same as that of FIG. 18 of the firstembodiment, but differs in that a transmission circuit controlling unit170 controls the transmission circuit unit 71 using the antennanumber/phase rotation amount notification signal notified from thereception circuit unit 72. The transmission circuit unit 71 is the sameas that described in FIG. 19, and will not be described in the presentembodiment. Moreover, the phase control information with which thetransmission circuit controlling unit 170 controls the transmissioncircuit unit 71 can be expressed in the manner shown in FIG. 29. FIG. 29is substantially the same as FIG. 20 of the first embodiment, differingonly the data signal portion for the antennas designated antennas number2 and 3, in that 2 πmT/Ts+θ2 is used as the phase control informationfor antenna number 2, and 2 πm2T/Ts+θ3 is used as the phase controlinformation for antenna number 3. The phase control information shown inFIG. 30 could also be used. The phase control information in FIG. 30 issubstantially the same as that in FIG. 29, with the exception of thephase control information related to the pilot channels at antennanumbers 2 and 3. In this case, phase control is performed not only byphase control information related to the data signal included in theantenna number notification signal notified from the terminal, but alsoby phase control information related to the pilot channel of θ2 forantenna number 2 and θ3 for antenna number 3, the use of phase controlinformation such as in FIG. 30 provides the distinction from FIG. 29.

Thus, by using a communication system including the terminal apparatusand base station apparatus set forth in the present embodiment, evenwhen the maximum delay time between antennas is small particularly shownin FIG. 3, a large multi-user diversity effect can be obtained byperforming the phase control described in the present embodiment.

While embodiments of the present invention have been described abovewith reference to the drawings, the specific structures are not limitedto those in the embodiments, and also include design within a scopewhich does not depart from the gist of this invention.

INDUSTRIAL APPLICABILITY

The present invention is well suited to use in a communication systemthat performs multi-carrier transmission between a terminal apparatusand a base station apparatus and performs scheduling by dividing intomultiple blocks in frequency and time domains, but is not limited tothis.

The invention claimed is:
 1. A wireless transmitter comprising: aplurality of transmission antennas; a phase rotating unit configured toadd a phase rotation to signals which are respectively input to theplurality of transmission antennas; and a reception unit configured toreceive information on a phase control of arbitrary antennas among theplurality of transmission antennas from another party of communication,wherein the phase rotating unit adds a first phase rotation forcontrolling a maximum delay time between the plurality of transmissionantennas depending on whether transmission is performed using afrequency diversity or a multi-user diversity and a second phaserotation for controlling phases of the arbitrary antennas among theplurality of transmission antennas based on the information.
 2. Thewireless transmitter as recited in claim 1, wherein the wirelesstransmitter is used in a transmission system in which scheduling ofusers is performed on a per-chunk basis where a region defined in afrequency domain and in a time domain is divided into chunks in thefrequency domain and in the time domain, and in the case in which thefrequency bandwidth of the chunk is Fc, the phase rotating unit adds thefirst phase rotation so that the maximum delay time between theplurality of transmission antennas is set to either a predeterminedfirst value which is smaller than 1/Fc or a predetermined second valuewhich is larger than 1/Fc.
 3. The wireless transmitter as recited inclaim 2, wherein the first value is zero.
 4. The wireless transmitter asrecited in claim 1, wherein a phase rotation amount added by the secondphase rotation is a predetermined value.
 5. The wireless transmitter asrecited in claim 4, wherein a plurality of values are prepared for thepredetermined value, and the information includes information fordesignating a value from among the plurality of values.
 6. The wirelesstransmitter as recited in claim 1, wherein the information includesinformation for designating an antenna to which the second phaserotation is added.
 7. The wireless transmitter as recited in claim 1,wherein the information includes information indicating a phase rotationamount of the second phase rotation which is added to the arbitraryantennas.
 8. The wireless transmitter as recited in claim 1, furthercomprising a transmission unit configured to transmit pilot channelscorresponding to the plurality of transmission antennas which areorthogonal to each other from the plurality of transmission antennas,respectively.
 9. The wireless transmitter as recited in claim 8, whereineach of the orthogonal pilot channels is generated by the multiplicationof an orthogonal code.
 10. The wireless transmitter as recited in claim1, wherein the phase rotating unit adds no phase rotation to a pilotchannel.
 11. The wireless transmitter as recited in claim 1, wherein thephase rotating unit does not add the first phase rotation to a pilotchannel.